In the prior art, the use of draglines wielding dragline buckets for excavating sites is well known. One example of their use is the removal of the overburden in open pit coal mines. Typically, the buckets have an enormous capacity and can weigh 60 or 80 tons. FIG. 1 shows a typical bucket which is designated by the reference numeral 10. The dragline bucket 10 includes sidewalls 11 connected at the bucket front end by an arch 12 and a bottom 13 terminating in a row of excavating teeth 14. The sidewalls 11 also include shackles 15 to which drag chains (not shown) are connected and trunnions 17 to which hoist chains (not shown) are connected. Since these buckets are conventional, a further description of the bucket structure or its use with a dragline is not deemed necessary for understanding of the invention.
One major problem with these buckets is the difficulty in moving the bucket from one location to another. Often times, the buckets must be moved between sites which are remote from each other and it is impractical for the dragline to accomplish such a task. In these instances, the buckets are often times merely dragged to the next site or placed on steel and the steel is dragged. This type of transport is inefficient since the bucket can not be dragged at any appreciable speed. In addition, the shear weight of the bucket, e.g., 120,000-160,000 pounds, can cause severe damage to the soil or landscape during the dragging process.
Dragline buckets can also be loaded directly on a trailer using the dragline itself. The problem with this loading technique is the difficulty in controlling the dragline bucket during trailer loading. The long lines of the dragline which support the bucket tend to swing the bucket. Consequently, there exists a substantial risk of damaging the trailer via contact with a swinging bucket.
In view of the inability to easily and efficiently move a dragline bucket from one site to another, a need has developed to provide an improved means of transporting a dragline bucket, one that is relatively quick and that does not harm the landscape.
In response to this need, the present invention provides a dragline bucket transporter and method of use which overcomes the disadvantages noted above. The invention is particularly adapted for use with a towing or hauling vehicle as disclosed in U.S. Pat. No. 5,435,586 to Smith that is hereby incorporated in its entirety by reference. Referring to FIGS. 2 and 3, the hitch assembly of the hauling vehicle disclosed in the Smith patent is designated by the reference 20 and includes a gooseneck 21, a tow-hitch assembly 23 and a grab hook assembly 25.
The tow-hitch assembly includes a tow-hitch 27, a post 28 extending from its distal end and a pivot pin 29. The tow-hitch 27 is raised and/or lowered by a hydraulic cylinder 31 and piston 33. Movement of the piston 33 drives the tow-hitch 27 about the pivot pin 29. The cylinder 31, although not shown, is fixed to the towing vehicle (also not shown).
The grab hook assembly 25 includes a grab hook 35 also pivotally mounted on the pin 29. The grab hook 35 is driven by a cylinder 37 and a piston 39, the cylinder 37 being pivotally mounted at 41.
The gooseneck 21 has a hook 43 at its distal end, the hook 43 including a concave surface 45. In conjunction with the surface 45 is a recess 47 in the base of the tow-hitch 27.
Still with reference to FIG. 2, the hitching assembly 20 is shown in combination with the end 50 of a low boy trailer. The trailer end 50 has a coupling 51, the coupling including a shaft 53 for engagement with the hook 43 of the gooseneck 21.
The trailer end 50 also has an upper surface 55 and a lower surface 57 which form a wedge-shape, the inclined upper surface 55 configured to interface with the base of the tow-hitch 27 when it is lowered for lifting purposes. The shaft 53 has spaces on either side to accommodate both the hook 43 and the grab hook 35.
In use, the hauling vehicle, having the hitching assembly 20 attached thereto, moves toward the low boy trailer end 50. During this movement, the hook 43 of the gooseneck 21 is positioned beneath the shaft 53. If misalignment occurs, the grab hook 35 can be operated to pull the shaft 53 onto the concave surface 45. The tow-hitch 27 is then lowered by extension of the piston 33, see FIG. 3, so that the tow-hitch 27 mates with the surface 55 of the trailer end. The tow-hitch force upon the trailer surface 55 causes the low boy trailer end 50 to raise. A lever action occurs at the pivoting point of the gooseneck where it is attached to the vehicle since the cylinder 31 is fixed to the hauling vehicle.
While the Smith patent suggests that a hauling vehicle with the hitching assembly 20 can be used to tow low boy trailers or other vehicles, there is no teaching or suggestion in this patent concerning moving dragline buckets or using the hauling vehicle for such movement.